Technical Field
The present disclosure relates to a power amplification module.
Background Art
A mobile communication device such as a cellular phone employs a power amplification circuit (power amplifier circuit) to amplify power of a signal to be transmitted to a base station. Recently, a modulation system, such as High Speed Uplink Packet Access (HSUPA), Long Term Evolution (LTE), or LTE-Advanced, as a high-speed data communication standard has been employed in a cellular phone. In such a communication standard, it is important to reduce shifts in phase and amplitude in order to improve the communication speed. In other words, the power amplification circuit is required to have high linearity. Further, in such a communication standard, the range of change in the amplitude of a signal (dynamic range) is often increased in order to improve the communication speed. Then, in order to increase linearity even when the dynamic range is large, high power-supply voltage is required, and this tends to increase the power consumption of the power amplification circuit.
In the meantime, the cellular phone is required to reduce power consumption in order to lengthen the time during which a call or communication is enabled. For example, Patent Document 1 discloses an envelope tracking system for controlling the power-supply voltage of a power amplification circuit according to the amplitude level of an input modulated signal in order to improve power efficiency.